波士頓爆炸案後美國全境提高安保級別

波士頓馬拉松爆炸案發生之後，美國國內從世貿中心、時報廣場，到白宮及各類體育場館均提高了安保級別，警方增派了重點場所的巡邏警力，並派出反恐小分隊參與安保工作。執法部門通過社交網站呼籲公衆向警方報告任何可疑行爲和活動。紐約市出動了危急情況反應小組和1000多名反恐工作人員，對帝國大廈、洛克菲勒中心和聯合國總部等人羣密集的場所進行重點監控。其他各州也都增加了警方巡邏密度，同時加強了對橋樑、隧道及鐵路線路的安全監控。與此同時，大洋另一邊的英國也在加緊爲週三的撒切爾夫人葬禮佈置安保方案，屆時女王伊麗莎白二世和各界名人均會出席。受波士頓爆炸案影響，英國警方正在重新審查將於本週日舉行的倫敦馬拉松的安保方案。

From the World Trade Center and Times Square in New York to the White House and sports venues across the country, police patrolled in packs and deployed counterterrorism teams Monday as security was stepped up after explosions at the Boston Marathon.

Worries also reverberated across the Atlantic, where an already robust security operation was being beefed up for Wednesday's ceremonial funeral for former Prime Minister Margaret Thatcher. The event at St. Paul's Cathedral, to be attended by Queen Elizabeth II and other dignitaries, calls for a procession through the streets of London, with Thatcher's flag-draped coffin carried on a horse-drawn carriage.

British police were also reviewing security plans for Sunday's London Marathon — the next major international race — because of the bombs that killed three people and injured more than 140 in Boston.

Across the U.S., security was tightened at landmarks, government buildings, transit hubs and sporting events. Law enforcement agencies also urged the public via Twitter and Facebook to report suspicious activity to the police.

In New York, authorities deployed so-called critical response teams— highly visible patrol units that move in packs with lights and sirens, — along with more than 1,000 counterterrorism officers. Highly trafficked areas like the Empire State building, Rockefeller Center, St. Patrick's Cathedral, the United Nations and the World Trade Center site were being especially monitored.

Mayor Michael Bloomberg said the police department was fully prepared to protect the city.

"Some of the security steps we are taking may be noticeable," Bloomberg said. "And others will not be."

In Washington, Secretary of Homeland Security Janet Napolitano urged the American public "to be vigilant and to listen to directions from state and local officials."

"At the president's direction, the Department of Homeland Security is providing any support necessary in this ongoing investigation," Napolitano said.

At the White House, the Secret Service expanded its security perimeter after the attacks, shutting down Pennsylvania Avenue and cordoning off the area with yellow police tape. Several Secret Service patrol cars blocked off entry points, although the White House was not on lockdown and tourists and other onlookers were still allowed in the park across the street.

Speaking late Wednesday from the White House, President Barack Obama declared that those responsible would "feel the full weight of justice," though he urged a nervous nation not to jump to conclusions and pointedly avoided using the words "terror" or "terrorism."

However, top lawmakers declared the deadly incident an act of terrorism, and a White House official said it was being treated that way.

Police in Los Angeles, Washington, San Diego, Las Vegas, Detroit, Atlanta and other major cities were monitoring events closely and assessing increases in security measures.

In California, emergency management officials activated their statewide threat assessment system, which was established after the Sept. 11 attacks. And officials in multiple cities and counties throughout the state were reviewing information from federal authorities for possible threats.

In Seattle, police increased patrols in neighborhoods and around government buildings and other facilities. In Colorado a statewide alert was sent out advising law enforcement agencies to look out for suspicious activities.

In New Jersey, authorities raised security statewide, calling in off-duty state police officers and deploying bomb units, aviation crews, tactical teams and search and rescue assets as a precaution.

Transit and port officials in New York and New Jersey were on heightened alert at bridges, tunnels and on rail lines between the two states, as well as on New York City's subway system and commuter rails.

And at the Port of Los Angeles and Long Beach, as well as at three major Los Angeles airports, including Los Angeles International, law enforcement officials were in a "heightened state of vigilance," with increased patrols, authorities said.